The present invention relates to tubular blind fasteners of the type that can be inserted through a pre-formed hole in a workpiece and secured therein by a setting operation carried out from one side of such workpiece. More particularly, this invention is directed to a blind fastener utilising a pull mandrel to effect the setting operation and which further has shock absorbing properties.
Many conventional assemblies, across through many different industries, utilise end-stops defining the limit of movement of particular slidable members. One example of such a stop member is an end-stop for sliding drawers in cabinets, desks and domestic cooker trays. Additionally, within the motor industry, it is known that the plastic carrier part of an electric window assembly (the carrier part that supports and carries the glass in a window winder application) travels along an appropriate metal track that acts as a guide for such carrier. The movement of the plastic glass carrier is usually achieved by means of an electrical motor whereby, commencing with the car window in an open position, the electrical motor upon operation causes the glass carrier to move upwardly to close the window at the top of the door. It is the action of the glass closing at the top of the door and encountering the doorframe that creates an electrical overload thus causing the motor to switch off. However, in the case of convertible vehicles, the car door does not have a top to the doorframe which can be used to provide a means of arresting the upward movement of the glass carrier. Therefore, a solid metal stop is provided in the metal rail along which the glass carrier travels to act as a stop means by physically engaging the plastic carrier. Obviously, plastic stop members or other resilient stop members would be too weak to withstand the overloading forces of the electrical motor commonly employed in electrical window winder designs and would fail to meet its objective. Therefore, rigid metal barriers are employed to achieve this function. However, the contact of the hard plastic of the carrier with the rigid metal stop creates a relatively large noise which, in today's automobile industry, is deemed unacceptable. Attempts to solve this problem by incorporating a soft pad to the glass carrier have proven to be expensive and not entirely satisfactory. Also, since the applied load of the glass carrier on this stop is substantial and applied at a distance from the stop securing point, there is created a relatively large pivotal force to be applied to the stop securing point which has a tendency to cause the stop to be torn from the metal rail. In addition, the cost of assembling a metal stop on such rail by welding or bolted fixings is relatively expensive and time consuming, particularly where significant volumes are required and access is necessitated to both sides of the rail, which has limiting design disadvantages in some designs of window winders.
It is therefore an object of the present invention to provide a blind fastener which can be used as an appropriate stop for arresting displacement of slidable members and which alleviates the aforementioned problems of existing stops, particularly those associated with window winders.